“The best lack all conviction, while the worst/Are full of passionate intensity.” These words, from WB Yeats’s poem The Second Coming, came to mind as I read the testimony from Wednesday’s Senate hearings on climate change.

They’re not a precise description of what took place, as the two most eminent climate scientists who testified before the environment and public works committee, Christopher Field and James McCarthy, were not lacking in conviction. But they were, as scientists should be, careful and meticulous, laying out their evidence calmly and sequentially, saying nothing that was not supported by the data.

By contrast, the Senate committee’s ranking member (its most senior Republican), James Inhofe, spoke with the demagogic passion of a revivalist preacher. “The global warming movement has completely collapsed … the science of the United Nations Intergovernmental Panel on Climate Change (IPCC) was finally exposed … The time has come to put these tired, failed policies to rest and embrace the US energy boom so that we can put Americans back to work, turn this economy around, become totally energy independent from the Middle East, and ensure energy security for years to come.”

In other words, Inhofe argued, we should take no action on climate change, which he has described as “the greatest hoax ever perpetrated on the American people”.

Never mind the overwhelming evidence that has accumulated since the last Senate hearings in 2009; never mind the crazy temperatures the US has been experiencing recently, which have alerted many Americans to what climate change is likely to deliver in the decades to come; never mind the prominent sceptic Richard Muller’s assessment of the evidence, which led to his change of heart. (It told us nothing we didn’t know already, but it should at least have caused the deniers to stop and think).

None of this makes the slightest difference to Inhofe. But how could it? Even if he were persuaded by the great weight of evidence for man-made climate change, changing his mind would be a very expensive decision. It could cost him his seat: not because it would necessarily be an unpopular shift – even in Oklahoma – but because it would jeopardise the massive flow of funds required to remain in high office in the US.

Take a look at Inhofe’s campaign funding. The major source, contributing half a million dollars over the past five years, has been the oil and gas industry.

Of his individual contributors, the biggest is Koch Industries – an oil, gas, minerals, timber and chemicals corporation, that is described by its owners, Charles and David Koch, as “the biggest company you’ve never heard of”. They fund a number of anti-environmental and anti-tax lobby groups. They set up the organisation which founded the Tea Party movement.

The second biggest contributor is Murray Energy, that boasts it is “the largest privately owned coal company in America”. The third is the oil and gas company Devon Energy. The fourth is the Contran Corporation, whose billionaire owner Harold Clark Simmons has a political profile similar to that of the Koch brothers.

If Inhofe were to change his position on man-made global warming, is it credible that he would retain all this funding? No. He receives money from fossil fuel companies because he articulates the views to which these funders subscribe, and because he advances their interests in the Senate. Given that keeping your seat means spending a fortune on television advertising and other forms of campaigning, changing your views on a matter of great interest to your sponsors is likely to be political suicide.

For people like the Kochs, Murray Energy and Harold Clark Simmons, the money they give to politicians is small change. For environmental campaigns, contributions of this size would break the bank. The money available to big business means that there will always be a massive asymmetry of this kind in the potential for political funding. As a result, a political system which imposes no effective cap on campaign finance leads inexorably to plutocracy: governance on behalf of the richest people and corporations.

The first prerequisite for protecting the environment is a functioning democracy. In any other system, those with the most money to spend or, in other circumstances, the most thugs to deploy, win the political battles. The further from democracy a nation strays, the greater the opportunities to destroy the world’s living systems, however unpopular that destruction may be.

The foremost threat to democratic values in countries like the US and the UK is the freedom with which billionaires and corporations can pay people and parties to represent their views. Protecting the environment, like protecting the welfare of a nation’s poorest and weakest people, requires a sweeping reform of political funding, on both sides of the Atlantic.

Monbiot.com